How do I transfuse platelets (PLTs) to reverse anti-PLT drug effect? (CME)

Clinical pharmacology of antiplatelet drugs

INTRODUCTION

Platelets play a key role in arterial thrombosis and antiplatelet therapy is pivotal in the treatment of cardiovascular disease. Current antiplatelet drugs target different pathways of platelet activation and show specific pharmacodynamic and pharmacokinetic characteristics, implicating clinically relevant drug-drug interactions.

AREAS COVERED

This article reviews the role of platelets in hemostasis and cardiovascular thrombosis, and discusses the key pharmacodynamics, drug-drug interactions and reversal strategies of clinically used antiplatelet drugs.

EXPERT OPINION

Antiplatelet therapies target distinct pathways of platelet activation: thromboxane A₂ synthesis, adenosine diphosphate-mediated signaling, integrin α_IIbβ₃ (GPIIb/IIIa), thrombin-mediated platelet activation via the PAR1 receptor and phosphodiesterases. Key clinical drug-drug interactions of antiplatelet agents involve acetylsalicylic acid - ibuprofen, clopidogrel - omeprazole, and morphine - oral P2Y₁₂ inhibitors, all of which lead to an attenuated antiplatelet effect. Platelet function and genetic testing and the use of scores (ARC-HBR, PRECISE-DAPT, ESC ischemic risk definition) may contribute to a more tailored antiplatelet therapy. High on-treatment platelet reactivity presents a key problem in the acute management of ST-elevation myocardial infarction (STEMI). A treatment strategy involving early initiation of an intravenous antiplatelet agent may be able to bridge the gap of insufficient platelet inhibition in high ischemic risk patients with STEMI.

Updates on management of nonvariceal upper gastrointestinal bleeding

PURPOSE OF REVIEW

Upper gastrointestinal bleeding (UGIB) is a common and life-threatening condition in the United States and worldwide.

RECENT FINDINGS

There have been several exciting recent advances in the endoscopic management of UGIB. One such advance is the recent approval of Hemospray by US Food and Drug Administration in May 2018. Another one is the emerging role of video capsule endoscopy as a triage and localization tool for UGIB patients. Finally, the development of new reversal agents for antithrombotic medications is an important advance in the management of life-threatening upper gastrointestinal bleed.

SUMMARY

In this article, we will broadly review the management of nonvariceal UGIB, focusing primarily on the data addressing these new advances.

Laboratory Monitoring of Platelet P2Y12 Receptor Inhibitors and Reversal of Antiplatelet Agents

OBJECTIVES

To review the use of laboratory tests for antiplatelet agents to determine escalation of antiplatelet therapy and for emergent reversal of P2Y12 inhibitors.

METHODS

A case scenario and review of cardiovascular and neurointerventional literature are described.

RESULTS

In cardiovascular disease patients, large randomized trials failed to demonstrate superiority of tailored antiplatelet regimens using the VerifyNow P2Y12 assay, where earlier studies had shown promise. Platelet transfusions restored platelet function measured by vasodilator-stimulated phosphoprotein, light transmission aggregometry, or thromboelastography but not VerifyNow P2Y12, with the most restoration for clopidogrel and the least for ticagrelor.

CONCLUSIONS

Current evidence does not support changing antiplatelet therapy based on the results of platelet function monitoring tests. For emergent reversal of P2Y12 inhibitors, test method can affect platelet dosing recommendations, as different methods may give different results.

No Benefit From Platelet Transfusion for Gastrointestinal Bleeding in Patients Taking Antiplatelet Agents

BACKGROUND & AIMS

Antiplatelet agents decrease cardiovascular events but increase gastrointestinal bleeding (GIB). Guidelines propose platelet transfusion for patients who take antiplatelet agents and have serious GIB. We investigated whether such patients are at decreased risk for rebleeding or increased risk for cardiovascular events after platelet transfusion.

METHODS

We performed a retrospective cohort study of patients with GIB admitted to Yale-New Haven Hospital from 2008 to 2013 who were taking antiplatelet agents and had platelet counts higher than 100 × 10⁹/L. Cases (patients who received platelet transfusion, n = 204) were matched with controls (no platelet transfusions, n = 204) for sex, age, and GIB location. The primary outcome was recurrent GIB. Multivariable regression analyses were performed to adjust for differences in baseline characteristics.

RESULTS

Cases and controls had similar proportions of GIB due to non-variceal upper GIB (117 of 204, 57% vs 115 of 204, 56%) and colonic GIB (80 of 204, 39% vs 81 of 204, 40%). Cases had more severe GIB than controls, which was based on lower blood pressure and hemoglobin levels and higher heart rates and the proportion admitted to intensive care. Univariate analyses showed that higher proportions of cases had major cardiovascular events (23% vs 13% for controls), died (7% vs 1% for controls), or had hospital stay longer than 4 days (47% vs 33% for controls). However, multivariable analyses showed a significant difference between cases and controls in only risk of death (odds ratio, 5.57; 95% confidence interval, 1.52-27.1). The adjusted odds ratio for recurrent bleeding was 1.47 (95% confidence interval, 0.73-3.05) for cases vs controls.

CONCLUSIONS

The use of platelet transfusions in patients with GIB who are taking antiplatelet agents without thrombocytopenia did not reduce rebleeding but was associated with higher mortality. At least some of the increase in mortality could be due to the residual bias of an observational study, but because of the lack of benefit, we do not support the use of platelet transfusions in patients with GIB who are taking antiplatelet agents.

Transfusion Medicine

Transfusion of various blood components can provide relief from symptomatic anemia and reduce the bleeding risks associated with low platelet counts or presence of coagulopathy. Blood components are collected from volunteer donors and processed into separate components to maximize efficient utilization of a scarce resource while also providing maximum clinical benefit. Tests including blood type and screening for clinically significant alloantibodies increase the likelihood of successful transfusion. Risks of transfusion include hypersensitivity and hemolytic transfusion reactions, transfusion-related acute lung injury, transfusion-associated circulatory overload, and transmission of infection. Indications for transfusion are reviewed along with various products available for transfusion.

Grading of peripheral cytopenias caused by nonalcoholic cirrhotic portal hypertension and its clinical significance

This study investigates peripheral cytopenias in patients with splenomegaly caused by nonalcoholic cirrhotic portal hypertension. Data from 330 splenomegaly cases caused by nonalcoholic cirrhotic portal hypertension were collected and analyzed using univariate and multivariate analysis. The cytopenias were scored and graded according to the F value of the multiple linear regression equation. Based on the severity of thrombocytopenia, cytopenia was graded as mild, moderate, or severe, and determined by a score of <2 points, 2-3 points, and >3 points. 30 % of the patients had monolineage cytopenias, 35.8 % had bilineage cytopenias, and 34.2 % had trilineage cytopenias. All patients were treated surgically. In the univariate analysis, the severity of erythropenia was different in the surgical outcome when compared to the intra-group (P < 0.05). In the multivariate analysis, thrombocytopenia was different in the surgical outcomes when compared with leukopenia and erythropenia (P < 0.05). There was a significant difference in surgical outcomes between the three grades (mild, moderate, and severe) of cytopenia (P < 0.05). Peripheral cytopenias have a significant impact on the clinical outcomes. The more severe the cytopenias, the worse the surgical outcomes are. Thrombocytopenia is a major factor influencing surgical outcomes. The thrombocytopenia-based three-level grading of cytopenias provides a basis for analyzing individual cases, planning treatment, and assessing prognosis in clinical practice.

Reversing the Effects of Antiplatelet Agents in the Setting of Intracranial Hemorrhage

Patients are increasingly being prescribed antiplatelet agents (APAs) for a growing number of medical and surgical conditions. These agents are associated with an increased risk of hemorrhage, including intracranial hemorrhage (ICH). In the setting of warfarin use and ICH, strategies to reverse the drug effects have improved outcomes. No such strategy exists for APAs, and these patients continue to have poor posthemorrhage outcomes. One strategy is the use of platelet transfusions to provide functional, circulating platelets. Studies have shown mixed results regarding the benefit of this practice. Other strategies include the use of desmopressin and recombinant factor VIIa. More studies are necessary to delineate the effectiveness of the various strategies.

Abnormal coagulation tests before kidney biopsies-what next?

Introduction

Bleeding is one of the most feared risks from a renal biopsy. To determine this risk, a clotting screen is performed prior to the biopsy to identify any coagulation abnormalities. In addition, concerns exist with respect to bleeding from platelet dysfunction and the special cases of paraprotenemia.

Method

Literature search of all the relevant articles in relation to bleeding risk from clotting abnormalities and platelet dysfunction in the setting of kidney biopsy was conducted.

Results

Bleeding risk from abnormal clotting screen is minimal in the absence of prior bleeding history in patients with renal disease. Administration of fresh frozen plasma in these cases is probably unnecessary and often causes delay in the procedure. In a similar way, platelet transfusions may not be appropriate in those with platelet dysfunction.

Conclusions

Global coagulation function tests are now available which need to be considered to determine bleeding risk before kidney biopsy, in conjunction with a good patient history.